The invention relates to the general field of insonification devices having a plurality of elementary ultrasonic transducers each having at least one electro-acoustic component, the plurality of transducers being distributed on a chassis so that the electro-acoustic components are distributed on a so-called “front” surface of the insonification device intended to be placed facing the medium to be insonified.
Electro-acoustic components, which are generally made in piezo-electric, piezo-composite materials or from semiconducting materials, for example capacitive micro-machined ultrasonic transducers (CMUTs), allow generation of high power ultrasonic waves with limited electro-acoustic efficiency.
Typically, for frequencies comprised between 100 kHz and 10 MHz, the electro-acoustic efficiency is between 40 and 80% for these materials. Also, a large portion of the energy which is not converted into ultrasonic waves is dissipated as heat in the transducer.
Too large heating during continuous operation of the electro-acoustic component for a period of several seconds may damage it, or even destroy it and this heating may even possibly deteriorate the mechanical portions which make it up or the adjacent ones.
This heating effect therefore presently limits the possibilities of generating very high acoustic intensities for long periods of several seconds. It is generally recognized that it is difficult to generate a power greater than 5 W/cm2 at the surface of the transducer for periods of the order of a few tens of seconds without too large heating.
There are solutions for dissipating the produced heat in order to lower the temperature at the transducer. A known solution consists of having a cooled fluid, generally water, circulate on the “front” face of the insonification device. In this case, with the liquid, ultrasonic coupling may be achieved with the medium into which the ultrasonic waves are focused.
However, the heat exchange surface remains limited to the “front” surface of the insonification device and does not allow sufficient removal of heat in the case when very high acoustic intensities have to be used.